In a stringed musical instrument, such as a guitar, the strings, placed under tension, extend unsupported between a first critical point usually formed by the nut positioned where the neck joins the head and a second critical point usually formed by a clearly defined point on the bridge positioned on the body. The strings are secured or fixed at one end on the body of the instrument to what is traditionally known as the tailpiece, strung over the bridge and extended past the nut at the transition from the neck to the head, and, for conventional instruments, secured at the other end to the tuning pegs where an untensioned string is tensioned and adjusted to a tuned pitched condition, proper playing pitch for play, or, simply, tuned condition; sometimes a nut arrangement is provided for a headless or tuning peg-less design. Further, it is known to those of ordinary skill in the art that the direction of the strings are generally parallel to both neck and the surface of the body despite instances where the string deviates from this direction at either or both the peg head or tailpiece. The tension of an individual guitar string is approximately 17 lbs at typical pitched conditions; anchoring or securely attaching the string holds the string to the instrument under normal conditions that often comprise an additional 10 lbs of tension per string under other certain circumstances.
The second critical point can be created as a part of a combined bridge and tailpiece structure. Traditionally, the size of the bridge element is quite small so as to create a clearly defined single point of contact between the string and the bridge element. It is between these two points that the playable string length is typically determined, sometimes referred to as the scale length. Adjusting the relative distance between the first and second critical points is called harmonic tuning or setting the intonation. Some bridges structures are individually adjustable, that is for each string, relative to the nut for achieving a more precise harmonic tuning. Usually this adjustment of the second critical point for harmonic tuning is carried out first and then the strings of the instrument are tuned to playing pitch. Often referred to the “setup”, it is not uncommon that further adjustment of the harmonic tuning is necessary for a variety of reasons, for example, including changing the brand of a string where the alloy of the strings is varied or when the gauge of strings the player chooses changes. The term “intonation module” herein is defined as a device, one for each string of a stringed musical instrument, as opposed to, say, the tremolo itself, comprising a bridge element forming a second critical point adjustably positioned relative to the body and relative to the nut or the first critical point for harmonic tuning, and includes one additional element, such as, for example, a tailpiece element for fixedly securing the associated string to the body, or an alternate tailpiece, or a string tuning element to pitch tune and/or adjust the tension of the associated string such as a macro-tuner or a fine-tuner or parts thereof. Intonation modules can include aspects such as a base, a front end or leading edge closer the nut, a rear edge or trailing edge further the nut, formed with recesses, restricted portions, hollow portions, etc., adjustably secured to a base plate that in some cases may comprise a tremolo in general or fulcrum tremolo in particular.
Often the typical construction of the strings, particularly for guitar and bass, includes a plain end and, on the other end, a “ball end” which being a washer-like addition is wrapped by the string itself into a larger form to help in “fixing” or securing the string on the instrument to the tailpiece. Alternatives to the traditional “ball-end” can include molded ends that are reminiscent of bullets in shape, Fender Musical Instruments sells strings with “bullet ends” and there are similar Floyd Rose Speedloader strings that include such variations on each end of the string. Accordingly, the term “ball-end” is used collectively herein defined to include both the traditional and/or novel end of strings, opposite the “plain” end, meant for attaching to the tailpiece element of the instrument. The tailpiece provides for an opening or recess sufficient in size to receive the strings of various diameters generally ranging from 0.007″ to 0.070″ or more while being smaller than the diameter of the ball end so as to limit the passing of the ball end through the opening or recess in order to secure or mount the individual strings to the body. The wrapping usually extends up to a ½″ towards the plain end and as such the position of the tailpiece structure relative to the bridge element must insure that the wrapping does not extend over the second critical point when arranged on the instrument; this wrapping, under normal circumstances, is not subject to stretch compared to the rest of the string. Stable fine adjustments of these and other elements have been a longstanding problem for stringed musical instruments.
In the relevant art, “anchoring” strings is often referred to as attaching or securing a string and understood with the limitation that the anchoring is sufficient so that the string is fixedly attached or secured to the instrument under the typical tensioned conditions of the string.
In the Proelsdorfer U.S. Pat. No. 2,304,597, string tensioning devices placed on the tailpiece for fine tuning the pitch of the strings of violins, guitars and the like, were disclosed; such pitch adjustment is quite limited in range, an interval falling between that of a whole tone and a minor third at best, and designed to offer the tuning of the strings a minor adjustment of pitch after the general tuning is achieved with the tuning pegs on the head of the instrument which traditionally first provides for raising and adjusting the tension of the strings to pitch from an untensioned condition. This is regarded as fine tuning and the apparatus for doing so, the “fine tuners”, usually comprise an adjustment knob or thumb screw.
It is known to those skilled in stringed musical instrument design and construction that various tremolos have been proposed and utilized for varying the tension of all the strings simultaneously for the purpose of creating a tremolo sound. Further, it is known to those skilled in the art that there are a great many commonly used names for such devices, such as tremolo, tremolo device, tremolo tailpiece, tremolo bridge, fulcrum tremolo, fulcrum tremolo bridge, fulcrum tremolo tailpiece, fulcrum tremolo bridge-tailpiece, vibrato, vibrato bridge, vibrato tailpiece, vibrato bridge tailpiece, etc.
In one specific species, known as the fulcrum tremolo, first introduced in Fender U.S. Pat. No. 2,741,146, shows and provides a device comprising a novel structure which incorporates the bridge and the tailpiece. The portion supporting the bridge elements is called the bridge plate or the base plate. Further, the both the bridge and the tailpiece elements connected to the base plate simultaneously move together as the fulcrum tremolo device is pivoted around the pivot axis. Accordingly, a singular and defining aspect of the fulcrum tremolo is that the harmonic tuning is upset as the device is pivoted; and, accordingly, for an instrument equipped with a fulcrum tremolo, restoring any or all of the strings to a proper pitched condition also simultaneously restores the harmonic tuning. The base plate upon which the individual bridge elements are adjustably secured has a beveled ridge portion which is secured to the instrument body by six screws permitting pivotal movement about a fulcrum axis which varies the tension on the strings and produces the desired tremolo effect.
In this first vintage system, herein referred to as Type I, the metal bridge elements of '146 are loosely held in place by a spring loaded attachment screw arrangement pivotally secured through openings in a small bent portion of the base plate farthest from the fulcrum axis. The bridge elements also incorporate setscrews for varying the relative height of the bridge elements and, therefore, height of the respective second critical points relative to the base plate and by extension, the body and neck. Later iterations of Fender '146 included pivotally supporting the fulcrum tremolo relative to the body by a riser posts arrangement adjustably connected to the fulcrum tremolo. The horizontal distance between the vertical centerline of each riser post is approximately 2.22″. Further, the distance from the pivot point to the second critical point not including the variable heights of the bridge elements is 0.25″ and the distance form the nut to the pivot is about 25.25″ since the Fender Stratocaster for which this fulcrum tremolo first appeared provided a 25.5″ scale length.
Typically, in order to facilitate the fulcrum tremolo pivoting about its fulcrum axis, counter springs are utilized to counteract or counter balance the pull of the strings. Counter springs are usually connected to the body of the instrument at one end and, on the other end, to a separate spring attachment means usually a block of metal, milled or cast or a combination of the two, which being secured to the bottom of the base plate by three screws 90 degrees to the base plate is often called a spring block. Upward pitch changes initiated by the use of the fulcrum tremolo in one direction can increase the tension of individual strings over the normal 17 pounds.
One of the most troublesome problems with prior art has been maintaining the initial tuning at proper playing pitch. When a musician plays on the string there is usually some kind of string stretch over time that results in the overall tuning going out of balance. Specifically, when the pitch of the string changes, the position of the fulcrum tremolo and the position of the second critical point relative to the nut changes which then alters the harmonic tuning.
Initial position refers to the specific equilibrium point between the tension of the strings and the tension of the counter springs at the intended tuned pitched condition of the strings when harmonic tuning is achieved. Often the pivot means is subject to wear and the tremolo does not always return to its initial position. Great care is required to establish an initial position that provides both the proper harmonic tuning and proper pitch tuning for each of the individual strings since both aspects of adjustment are interactive.
Improvements to the Fender '146 fulcrum tremolo have included using string clamps at the nut and at point on the opposite side of the intonation point or second critical point on each of the bridge elements relative to the nut in order to limit string stretch to the portion of the string within these two points defining the scale length; and, separately, adopting a novel shaped beveled edge, called a “knife edge”, adjustably supported by two screw-like members called riser posts positioned in the body to improve the return to initial position after pivoting the fulcrum tremolo device (Rose U.S. Pat. No. 4,171,661). The knife edge fulcrum arrangement provides for the base plate to be positioned generally parallel to the instrument body and offers the novel possibility to increase the tension of the string for upward pitch changes; this feature can increase string tension well beyond the normal approximate 17 lbs of tension at typical playing pitches.
In this second vintage system, herein referred to as Type II, the horizontal distance between the vertical centerline of each riser post is approximately 2.925″. The distance from the pivot point to the second critical point, not compensating for the variable heights of the bridge elements, is 0.50″ and approximately 25.00″ from the first critical point on the nut for instruments with a 25.5″ scale length. This greater distance of 0.50″ relative to Fender's 0.25″ provides an additional area on the leading edge portion of the base plate, the area located closest to the nut. The Rose assembly bridge-tailpiece extra portion then includes a fork-like slot arrangement extending between the bridge portion and the leading edge of the base plate. An attachment screw is positioned within the fork-like slot for threadedly attaching the Rose improvement to the base plate. Accordingly, sliding the fork-like portion and, therefore, the Rose assembly in the direction of the string adjusts the harmonic tuning of the string.
In Rose U.S. Pat. No. 4,497,236 a combination of the bridge element, the tailpiece and tuners replaced the “novel structure” of the Fender device so that within the limited range (typically within a range about the interval of a whole tone, for example from C to D in the Western diatonic musical scale) the strings could be re-tuned without first unlocking the string clamps at the nut. However, string stretch beyond the range of the fine tuners necessitated a correction that is tedious and time consuming involving unlocking the string clamps, re-tuning the strings, re-clamping, and further re-tuning the string with the fine tuners and then re-tuning all the other strings to re-balance the equilibrium point back to initial position. The string clamps of the Rose fulcrum tremolo comprise a conditional tailpiece and are characterized by small blocks slideably mounted within a recess within a housing element connected to the bridge element. The player, as a first step, typically cuts the ball-end of the string off, and then, in a second step, places the cut end of the string vertically or transverse the body within the recess between the block and a vertical surface located closest to the bridge element, then, in a third step, tightens an adjustment bolt against the block to, thereby, fixedly secure the string to the intonation module to create the functioning tailpiece, in a fourth step bends the remaining portion of the string approximately 90 degrees over the bridge, in a fifth and sixth step, secures the free end of the string to the tuning pegs for tensioning the string to proper playing pitch—in a some instances, there are later designs that while they do not require the ball end to be cut off for the clamping mechanism to fixedly secure a string, nonetheless show a design that requires the approximate 90 degree bend proximate the bridge element.
Each block is adjustably secured by an adjustment bolt aligned in the direction of the strings—threading the adjustment bolt slideably positions the block against the plain string end and clamps the string end between the block and a vertical surface of the recess in housing element. A first portion is formed parallel the instrument body that is the functional equivalent of the base plate of Fender '146 for securing the bridge elements. Adjustment bolts, one for each block, extend through slots formed in a second portion of the base plate fashioned to be simultaneously rising away from the body and nut at an angle. The second portion includes fine tuner screws threadably positioned transverse the direction of the strings that make variable contact with the adjustment bolt. Threading the fine tuner screw collectively pivots the position of the block and the housing element connected to the bridge portion as well as the bridge portion and the adjustment bolt about a separate axis parallel to the fulcrum axis for fine tuning the tension of the string.
Therefore, for stringed musical instruments, as is known to those skilled in the art:                The second critical point is a clearly defined point on the bridge or individual bridge elements, the adjustment of which relative to the first critical point on the nut defines the length of the string or scale length and the adjustment of which is called harmonic tuning.        
For fulcrum tremolos as originated by Fender U.S. Pat. No. 2,741,146, when pivoted:                Both the bridge portions and the string anchoring means, the tailpiece, simultaneously move about a fulcrum axis;        The harmonic tuning is upset; and        Various factors can disturb the equilibrium point between the tension of the strings and the tension of the counter springs and as a consequence disturb the initial position.        
For those fulcrum tremolos equipped with fine tuners as with Rose U.S. Pat. No. 4,497,236, Storey U.S. Pat. No. 4,472,750 and Fender U.S. Pat. No. 4,724,737:                The bridge and tailpiece portions simultaneously move about the fulcrum axis when the device is pivoted for the tremolo effect;        The fine tuner screws simultaneously move with the bridge and tailpiece portions about the tuning axis when fine tuning; and        Fine tuners are designed to offer the tuning of the strings a minor adjustment of pitch after the general tuning is first achieved, typically, by the tuning pegs on the head of the instrument; and        Adjusting the tension of a string by the fine tuner knob alone simultaneously adjusts the harmonic and pitch tuning and can achieve tuning a string to proper pitch conditions while simultaneously achieving proper harmonic tuning.        
For those fulcrum tremolos fitted with string clamps at the first and second critical points as in Rose U.S. Pat. No. 4,171,661,                String stretch beyond the clamps at the first and second critical points is eliminated offering the most stability of tuning possible;        A plain end of the string is inserted between the bock and a vertical surface formed in a recess in the housing element and clamped by threading an adjustment bolt; the adjustment screw is pivotally positioned in the direction of the strings and the fine tuner adjustment screw is both transverse to the adjustment bolt and direction of the strings.        
These two vintage fulcrum tremolos of the last century, Fender in the 50's and Rose in the 80's, are in part distinguished by the differing standards in the spacing between the riser posts, 2.22″ and 2.925″ respectively; and the relative distance between the riser posts and the first critical point on nut on the one side, 25.25″ and 25.00″, respectively, and, from an overview perspective, 0.25″ and 0.50″, respectively, from the pivot point to the second critical point on the bridge on the other.
The individual parts of the two vintage designs were generally not compatible. Consequently, those who had guitars with the 2.925″ spacing were limited to tremolos that had fine tuner arrangements and string locks and those guitars with the 2.22″ spacing were limited to those tremolos without fine-tuners and string locks.
Further improvements in the fulcrum tremolo in the 90's and into the new millennium utilized various novel arrangements for pivoting that included at least a portion of the surface of a ball bearing at the pivot point adjustably mounted to the body which not only improved return to initial position after use of the tremolo but also virtually eliminated the wear and tear associated with prior art (McCabe U.S. Pat. Nos. 5,965,831, 5,986,191, 6,175,066, 6,563,034, 6,891,094 and 7,470,841).
The evolution from fine tuners to macro-tuners on a fulcrum tremolo (McCabe U.S. Pat. Nos. 5,965,831, 5,986,191, 6,175,066, 6,563,034, 6,891,094 and 7,470,841) provided an intonation module that included a novel integrated bridge-tailpiece structure secured to the base plate of a fulcrum tremolo wherein the improvement included the broad provision to bring and adjust the strings to playing pitch from an untensioned condition circumventing the re-tuning limits imposed by the Rose clamps. Further distinguishing the art, various improvements positioned between the second critical point and the tailpiece portion are provided so the length of the string between these two areas is substantially inextensible in each of the macro-tuner examples. In each case the improvement comprised a novel portion that is positioned in a creative position for limiting the stretch of the string as outlined above while allowing the adjustment knob to be threaded to achieve macro-tuning '094 presents a novel quick tuning macro-tuner designed to bring each string to proper playing pitch in a first step and then further tuned by a separate fine tuner knob.
Macro-tuners refer to tuners with the capacity to raise and adjust the tension of the strings from an untensioned condition to a proper playing pitch, and as such provide for alternate tunings and compensation for substantial string stretch during the life of the string essentially without additional means.
Other improvements as disclosed in McCabe '831, '066, '094 and 191 included “tiers” or “steps” positioned on the base plate of the fulcrum tremolo, one for each bridge element or intonation module, that in displacing their relative positions create a radius for the strings in relationship to the radius of the fingerboard.
McCabe '034 discloses a modular fulcrum tremolo system with standardized base plate features available both the 2.925″ spacing and 2.22″ spacing where all the parts other than the base plate, such as the intonation modules solid or folded, with or with out macro-tuners, the global tuners, the tremolo arm assembly, etc. are interchangeable. Consequently, anyone can have simple intonation modules or macro-tuners regardless of the stud spacing and position present on the instrument.
McCabe '841 and '034 provide an unitary base plate formed, in one instance, by stamping and folding metal into a form that integrates the base plate with the spring block. Other features included bending a first portion of the base plate into a hinge-like form closest to the bearing axis creating a housing for receiving the bearings and/or the shaft for pivotally supporting the bearing assembly. Optionally, a cylinder for receiving the bearings can be fashioned for the same purpose and welded, for example, to the base plate in the same position. And in either case the dimensions of this portion reflects the spacing differences between the two vintage standards. Features also included “coining” a radius into the base plate, for example, in a series of steps or tiers to account for the radius of the fingerboard and eliminating the requirement of individual bridge element height adjustment screws so that the entirety of the bridge elements rest on the base plate maximizing acoustic coupling. “Coining” refers to that process in the stamping of metal that provides for a “relief” in the “landscape” of the object being formed.